The present disclosure relates to a semiconductor optical integrated device and a method of manufacturing the same.
Recently, a higher performance is required for a semiconductor optical integrated device from a viewpoint of advancement of optical communication and cost reduction. Further, in order to integrate a plurality of optical devices in a single semiconductor device, different waveguide structures suitable for each function of devices are used in the same semiconductor device (see, for example, Japanese Laid-open Patent Publication No. 2013-25242). For example, the different waveguide structures are used in the same semiconductor device in such a manner that an buried hetero structure waveguide structure having high current injection efficiency is used in a region serving a light emitting function of a semiconductor optical integrated device and a deep ridge waveguide having a low bending loss is used in a region serving a function of bending a waveguide.
Known examples of the case where it is necessary to form a plurality of waveguide structures on the same semiconductor optical integrated device include the following cases: a case where a laser oscillating portion is formed using a buried hetero structure waveguide and an arrayed waveguide diffraction grating (AWG) is formed using a deep ridge waveguide (see, for example, Japanese Laid-open Patent Publication No. 2002-232069); a case where a laser oscillator is formed using a buried hetero structure waveguide and a ring resonator is formed using a deep ridge waveguide (see, for example, Japanese Laid-open Patent Publication No. 2011-108829); and a case where a laser oscillating portion is formed using a buried hetero structure waveguide and a modulator is formed using a deep ridge waveguide (see, for example, Japanese Laid-open Patent Publication No. 2012-079990 and Japanese Laid-open Patent Publication No. 2010-226062).
The buried hetero structure waveguide and the deep ridge waveguide have different characteristics, and thus, it is possible to realize a multi-function and high-performance optical integrated device if the different waveguides are suitably used for each device integrated in the single semiconductor optical integrated device. However, when the buried hetero structure waveguide and the deep ridge waveguide are integrated using the conventional method, there is a problem that it is difficult to sufficiently exhibit the performance as the semiconductor optical integrated device since each optimal design is different between the buried hetero structure waveguide and the deep ridge waveguide.
That is, when the optimal design for the buried hetero structure waveguide is conducted in the same semiconductor optical integrated device, it is not the optimal design for the deep ridge waveguide so that the performance of the deep ridge waveguide is suppressed. Conversely, when the optimal design for the deep ridge waveguide is conducted, it is not the optimal design for the buried hetero structure waveguide so that the performance of the buried hetero structure waveguide is suppressed. In this manner, when the buried hetero structure waveguide and the deep ridge waveguide are configured in the same semiconductor optical integrated device, there is a trade-off relationship of performance between the buried hetero structure waveguide and the deep ridge waveguide.